A number of subscription on identical Apple ID, In-App buy IOS

APPLE ID IS SAME

Please attempt to perceive my scenario by an instance.

Now we have three plans on App Retailer.

1. one month
2. three months
3. one 12 months

Is that this default behaviour of the app retailer in-app purchases, Am I lacking one thing or doing one thing mistaken.

Is it actually not doable to buy two subscriptions from identical Apple ID and each bought renew parallely.

Please word these all circumstances are for identical Apple ID.

I signed up as Consumer A and bought one month subscription efficiently.
I logged out from Consumer A and signed up as Consumer B and tried to buy one month subscription, I bought error that subscription is already lively.
Now once more tried to buy three months plan, buy is successfull however what occurred after I once more logged in as Consumer A, then his subscription didn’t get renewed. I’m not getting any hook to cancel or expire the Consumer A subscription.